Hello, I'm new to this forum and was hoping to gain some insight from those of you who are clearly knowledgeable when it comes to everything houseboat.


Here's a little background:

 

My family is buying into a houseboat and we are trying to figure out a reliable and economical solution for power. We have discussed a few options but none of us has enough electrical knowledge nor experience to really know what's best for our situation. Our boat is 50ft x 17ft and our power needs will come down to playing a stereo, a television, lights, and plugging in an appliance or two throughout the day. (Usually we're on the boat for 3 nights max per visit . One of our friends recommended a marine generator along with an 18 marine battery system, an inverter and 4 solar panels which we think is major overkill in terms of need and cost.

 

As I do more research, it seems like we may be able to get away with 6-8 6V golf cart batteries and 2-3 solar panels. We think we should use a gas generator for charging the batteries when needed and for using a 110 system for the appliances.

 

Based on that info, can anyone provide insight and let us know if we're on the right track??

 

Thanks so much in advance.

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Harvey

Welcome Aboard!!

What about air conditioning and heating?

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Banana Tom

Thanks for the reply.!

As far as a/c and heat, we're not planning on either.

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Harvey

If you're only going to be out for 3 days max, I'd consider the battery bank and inverter, and carry a portable generator for backup. I love solar panels but they ARE expensive, and don't come into their own on short trips.

With enough batteries you can charge them at the dock before you leave; go out for 2-3 days and with any luck never have to listen to the genset. Your fridge if you have one will be the biggest load at 100-150 amp hrs per day. The rest is a matter of reading labels and doing the math.

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

Thanks Willie!

Our houseboat is floating on the ball so there is no way to charge batteries at the dock. I think it's still worth it to have solar so that when we arrive at the boat we have fully charge batteries to start our weekends...right?? From the minimal research I've done, it appears we could get two 125W panels for ~$1400. Do you think that would suffice with 6-8 golf cart batteries?? (Our fridge runs on propane so we don't need to account for that).

Thanks again!

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Harvey

If you don't have shore power available then solar panels are a given. Two 125's should do you quite well, if you're not running a fridge. Not sure where you are but I do fine with two 120's and two 50's (340w total) and I'm running an electric fridge 24/7. I have 6-6v batteries. The system will run my boat all spring and summer without any problems. This time of year with all the clouds it needs a little help. It's still good for several days on the hook, but by then I get bored anyway and decide to go "somewhere" and the engine alternator picks up the difference.

You should be able to get your two 125's for about $1200 http://www.windsun.com/ However with that kind of power you'll DEFINITELY need a charge controller, another $200 or so. So your estimate of $1400 is pretty close. A battery monitor is a good investment, another $160. The above site has everything, and lots of good info as well.

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

Edited: 09/19/2007 at 07:35:04 AM by stmbtwle

Willie, that's great info. Thanks so much.

Along with your fridge, do you also have a television and stereo? Also do you run a 110v system for appliances??

That's interesting about the alternator. Wondering if that might be a better choice for us in lieu of a generator..??

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Harvey

I just upgraded to a 1800w inverter and put the whole boat on it; so yes I can run a coffee pot or other portable appliance, or the TV. Stereo is an automotive 12v type. Lights are mostly 12v fluorescents and oil lamps.

What you can run and for how long all depends on your battery capacity. This is why you have to sit down and read labels and make HONEST assessments when sizing your system. The more STUFF you have the more batteries you'll need; and the more charging capacity you'll need too. You'll find it pays to be conservative. This is why a battery monitor is important; it makes power management something more than a wild-a$$ guess.

AC, stove, and hot water are not practical, they simply take too much power. I'm guessing your stove and water heater are gas, like mine.

I have an inboard diesel, so whenever it's running the alternator is charging. However I do NOT run it at anchor; it's only available when I am moving around. I used to carry a Honda 1000 generator; I hated the noisy contraption and the gasoline I had to carry for it. Once I upsized the solar array I didn't need it any more; but I still take it on trips, for emergencies.

You can make a 12v high-capacity charger out of a lawnmower engine and an alternator, but who wants to listen to a lawnmower when on a boat???

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

Yep..Stove and Hot water heater run on gas.

I'm getting the sense that if we go with 6-8 batteries and 250-300w of panels we should be in good shape based on our situation. We could then consider whether we want to keep a portable generator on the boat (those Honda EU2000i's look like a great option) or go with alternators on our two Mercury engines.

You're right, we need to sit down and crunch the numbers to get a more accurate assessment.



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Harvey

I would think with your load that 6 batteries and maybe as few as 120-200 watts of solar would handle your load, BUT I don't know where you are located and how you use our boat. When it comes to solar, more is merrier but it's also more expensive, and you have to draw the line somewhere.

A panel rated at 120 watts will in theory give you 10 amps of power but you'll rarely get this much. A lot depends on latitude, cloud cover, temperature, panel inclination relative to the sun, battery state-of-charge, etc. And just because the sun is up for 12 hrs a day doesn't mean you'll get 12 hrs of EFFECTIVE sun to the collectors. For a clue on how to estimate all this go to http://rredc.nrel.gov/solar/codes_algs/PVWATTS/. Anyway, if you don't have enough, the batteries may go dead; too much, it'll simply shut down when the batteries are charged. Your call.

Bear in mind if you only use your boat for 3 days a week you don't need enough solar to carry the full load; you just need enough to RECHARGE your batteries over 7 days what you took out in 3. How you recharge the batteries doesn't really matter; you can use solar, a windmill, a gas generator, your engine alternators, or a combination of all of them.

Using the engine alternators only makes sense if you're moving, then it's "free". Running a big engine at fast idle for hours to charge your batteries will get expensive. That's why we have dedicated gensets. If you cruise a lot the alternators can provide a lot of power; if you like to go out to some cove and anchor up for the weekend they don't.

Running ANY gas engine at the dock or at anchor presents a carbon monoxide problem. You have to be careful where you locate your generator (actually it's exhaust) and a carbon monoxide detector is a MUST. Your life depends on it. Then there's the noise factor. The constant buzz of a genset (quiet as some are) can still get irritating, if not to you then other boats in your vicinity.

All the above is about generation. Now about consumption. On your boat with the gas fridge your lights are probably the biggest energy hog. Replace everything you can with fluorescent lights or better yet LEDs. Fluorescents use 1/4 the power of regular bulbs. LED's are better yet but still pretty expensive. Lights you rarely use aren't on enough to matter, but lights in the galley and living area can eat up a lot of power. Look into replacing them with something more efficient.

Pay attention to your instruments. So often I hear about someone going out for the weekend and Sunday morning they get up and everything is dead as an anchor. That should NEVER happen, but only proper power management will prevent it. That's why the battery monitor is so important. A simple voltmeter is NOT enough. IMO the battery monitor should be the FIRST thing you install, it'll help you determine how much you are using, and how/where you can conserve. Then you can size your battery bank. Then you can figure out how much $$$$ solar or other charging capacity you need.

Let's say after all is said and done you figure you use 100 amp-hrs per day. For a three day weekend that's 300 amp hours. You don't want to discharge your batteries more than 50% so you need 600 amp hours of batteries @ 12 volts. That'll work out to 6 golf cart batteries, about 660 amp hours.

You know you won't use the boat for the rest of the week, so you need to recharge at least 43 amp hours per day. Not every day is sunny so let's say 80 amp hrs per day x 12 volts or 960 watt hrs. You go to the site above and discover that for a 1kw array you can get 4 kw-hrs of energy per day. working backwards, 960 watt hrs/4 hrs =240 watts of panels required.

However if you only use 50 amp hours per day you only need 4 batteries and 120 watts of solar. And save some $$$.

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw

Edited: 09/21/2007 at 07:39:02 AM by stmbtwle

Nice post Willie.

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Banana Tom

Willie, that's awesome! Great insight..exactly what i'm looking for. To say I'm uneducated when it comes to amps/watts/volts would be a big understatement.

btw, I'm located in northern california...about 90 miles south of sacramento.  90% of our boat usage is during the summer months and we pretty much have sun everyday in the summer.

where shall i  send the check for the consulting fees?  

Thanks again!

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Harvey

Thanks... I was afraid I was getting a bit wordy. No charge for the info, just passing on what I've learned (been there done that, warn't cheap, neither)

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Willie
She's a tired old barge but she's paid for! http://s71.photobucket.com/alb...p;current=ef324993.pbw